Ultrasonic power sensory system

ABSTRACT

A system includes a first transducer and a second transducer coupled together through a coupling medium communicating undulating pressure wave from the first transducer to the second transducer for the transfer of electrical power from an external controller energizing the first transducer transducing the power signal into an undulating pressure wave communicated through the medium to the second transducer traducing the undulating pressure wave into an electrical response signal that can be converted into useful power for powering an embedded sensory and actuation control unit. The primary advantage of the system is the transfer of power through a coupling medium without the use of electrical power wires.

STATEMENT OF GOVERNMENT INTEREST

The invention was made with Government support under Contract No.F04701-93-C-0094 by the Department of the Air Force. The Government hascertain rights in the invention. The invention described herein may bemanufactured and used by and for the government of the United States forgovernmental purpose without payment of royalty therefor.

REFERENCE TO RELATED APPLICATION

The present application is related to applicant's copending applicationsentitled Ultrasonic Data Communication System, Ser. No. 08/947,377 filedOct. 8, 1997, now U.S. Pat. No. 5,982,297 and Ultrasonic PowerCommunication System, Ser. No. 08/947,376 filed Oct. 8, 1997, now U.S.Pat. No. 6,037,376 by the same inventor.

FIELD OF THE INVENTION

The invention relates to the field of undulating pressure wavetransducers including acoustic, sonic and ultrasonic transducers,devices and systems. More particularly, the present invention relates tothe communication of power and or data signals communicated between twoultrasonic transducers separated by and communicating ultrasonicundulating pressure waves through an ultrasonic coupling medium.

BACKGROUND OF THE INVENTION

Devices and systems having transducers which transduce electrical energyto and from undulation pressure waves such as audio, acoustical, sonicand ultrasonic pressure waves, have existed for some time. Suchtransducers may include crystal, piezoelectric, magnetostrictive,inductive, vibrating, diaphragm, audio, acoustic, sonic, subsonic andultrasonic transducers, among many other exemplar types of transducers.In a forward direction, the transducers are coupled to sources ofelectrical energy having frequencies of respective energizing signals atthe resonant frequencies of the transducers for efficient transfer ofenergy from the electrical energy sources to the transducers thenimparting energy in the form of the oscillating undulating pressurewaves to loads coupled to the transducers. In a reverse direction, thetransducers receive energy of undulating pressure waves from sources ofundulating pressure waves and transduce the energy of those undulatingpressure waves into electrical energy delivered to loads of electricalenergy.

U.S. Pat. No. 3,958,559 entitled Ultrasonic Transducer teaches anultrasound pulse echo imaging system using piano concave lens ofelliptical shape positioned in front of the transducer for producing anextremely narrow ultrasonic beam and providing a large aperture tomaximize ultrasound power output from the transducer and capture angleof reflected echoes. The transducer both sends through electricalexcitation and receives ultrasonic wave beams generating electricaloutput signals. The transducer is a conventional flat disc transducerproducing an essentially collimated beam of ultrasound of frontalparallel pressure waves but having an ellipsoidal plano concave leansdisposed in the front of the transducer though bonding or positioningusing a coupling medium. The produced ultrasonic wave intensity may havea uniform, Gaussian, or some other desired distribution. Other types oftransducers may be shaped to include a transmitting receiving curvedsurface for focused transmission and collective reception of theultrasonic waves. Various types of transmitting and receivingtransducers having coupled lens or curved surfaces for focusedtransmission and collective reception of ultrasonic waves are well knownby those skilled in the art of ultrasonic transducer designs.

U.S. Pat. No. 4,368,410 entitled Ultrasound Therapy Device teachesmaintaining constant electrical energizing power to a transducerregardless of the load on the transducer using an analog servo feedbackcircuit. The device may be operated to emit an ultrasonic frequency anddriven by continuous wave signals, or pulse mode signals where the pulseperiod and duration are selectable using operator switches. The pulserange may be between ten and five hundred microseconds. Negativefeedback signals representing current and voltage drawn by thetransducer are supplied to an analog multiplier where the actual powerdelivered to the transducer is calculated and used to maintain the powerdelivered to the transducer. Comparators are used to supply errorsignals for open and closed circuit conditions to prevent loss ofcoupling or overheating of the transducer. These types of closed loopcontrol and sensing systems, methods and implementing devices are wellknown by those skilled in the art of transducer device and systemdesign.

U.S. Pat. No. 4,966,131 entitled Ultrasound Power Generating System withSample Data Frequency Control teaches the use of a disk shaped crystaltransducer actuated by an electrical power source having a controlfrequency for the efficient coupling of electrical energy into acousticenergy injected into a human body. The system includes the crystaltransducer having excitation electrodes and radio frequency (RF) poweramplifiers for supplying electrical power to the transducer. The systemincludes a single chip microprocessor having analog to digitalconverters, digital to analog converters, input-output communicationmeans, on board random access memory (RAM) and read only memory (ROM)for operational sensing and control of electrical circuits including anRF signal sensor and a voltage controlled oscillator for controlling theexcitation frequency to efficiently deliver electrical power to thetransducer then providing desired acoustic energy to a human load. Thesetypes of microprocessor and connected circuit designs for electricallydriving ultrasonic transducers are well known by those skilled in theart of transducer device and system designs.

U.S. Pat. No. 5,396,888 entitled Non Contact Tonometer and Method ofUsing Ultrasonic Beams teaches an ultrasonic transducer directing anultrasonic beam which is detected by an ultrasonic or optical means. Anultrasonic beam is used for ranging measurements. The ultrasonictransducer may be activated by continuous wave of pulse mode signalsusing electronic feed back control. High ultrasonic frequencies between100.0 KHz and 1.0 MHz are used to energize a transducer generating andprojecting the directed ultrasonic beam. The ultrasonic beam can bemodulated, directed and focused by conventional means. The ultrasonicpower level can be modulated at high frequency to enable phase sensitivedemodulation for detection. High bandwidth servo loops can control theintensity of the ultrasonic beam. The ultrasonic beams produce apressure field with a Gaussian profile. The transducer may be apiezoelectric crystal, magnetostrictive element or a vibratingdiaphragm, among others.

This patented transducer system comprises a plurality of coupledtransducers, a primary transducer for transmitting the directedultrasonic beam and secondary transducers for detecting the effect ofthe primary directed beam communicated at least in part through acoupling medium. The primary transducer is activated by an oscillatorproducing an amplitude modulation of an ultrasonic frequency signal. Onesecondary transducer detects a reflected ultrasonic beam indicating theamount of indentation effect of the primary ultrasonic beam on human eyetissue reflecting the transmitted beam. Another secondary ultrasonictransducer is for detecting and measuring the power transmitted and forcontrolling the amount of power transmitted by the primary transducer.Another secondary ultrasonic ranging transducer is colocated with theprimary transducers and is used for detecting the transmitted beam foraligning the primary transducer with the eye load. The secondarytransducer for measuring the indentation can be switched from eithertransmitting or receiving the directed ultrasonic beam. Transducer inputand output signals can be modulated and demodulated for signaltransmission and phase detection using conventional mixers and phasedetectors. Systems and devices for generating, directing and focusing aprimary transducer beam through a coupling medium for subsequentdetection by a plurality of secondary transducers are well known bythose skilled in the art of ultrasonic transducer device and systemdesign.

Those skilled in the art of transducer devices and systems are welladept at configuring specific transducers and electronic components forgenerating undulating pressure waves transmitted into and or receivedthrough a coupling medium for detecting information about the medium orits contents. However, those transducer devices and systemsdisadvantageously rely only on the sensing of the acoustic transmittingand reflecting properties of the medium and or its contents to obtaininformation about the system.

There are many applications that sense critical operating parameters ofa component in which it is exceedingly undesirable to connect electricalwires between the power supplies and the sensors, actuators,controllers, processors, and transmitters and receivers.

Continuing progress in Micro Electro Mechanical Systems (MEMS) has ledto the development of advanced, miniaturized, multi-functional systemswhich provide improved capabilities for sensing, monitoring and controlof various parameters and functions at very low power to enhance thehealth, safety, and reliability of current generation spacecraft andlaunch vehicles, as well as on newly emerging concepts for miniaturespacecraft. Such devices are also useful in terrestrial applicationssuch as motor vehicles and structures. Current MEMS devices often takeadvantage of manufacturing technologies developed for microelectronics,along with subscaled applications of macroscopic devices such as valves,pumps, or power systems. Typical MEMS systems disadvantageously requirethe use of external power supplies and data processors for controllingthe operation of systems and sensing information about systems. Manyapplications of micro devices, particularly micro sensors, require thatthe devices be wireless. This has led to devices having limitedusefulness and lifetime due to the limited capacity of on boardbatteries. These and other disadvantages are solved or reduced using theinvention.

SUMMARY OF THE INVENTION

An object of the invention is to provide a system for transmitting powerthrough a coupling medium communicating undulating pressure wavesbetween opposing transducers.

Another object of the invention is to provide a system for transmittingdata through a coupling medium communicating undulating pressure wavesbetween opposing transducers.

Yet another object of the invention is to provide a system fortransmitting power and or data through a coupling medium communicatingundulating pressure waves between opposing transducers to supply powerto embedded sensors or actuators without the use of electrical wiresextending through the coupling medium.

Yet a further object of the invention is to provide a system fortransmitting power and or data through a coupling medium communicatingundulating pressure waves between opposing transducers to supply powerand to communicate data to an embedded processor for controllingembedded sensors and or actuators without the use of electrical wiresextending through the coupling medium.

The present invention is primarily directed to wireless embeddedmicrosensor and microactuator systems and other wireless devicesparticularly using transducers generating undulating pressure waves forpower transmission for powering embedded wireless devices. In anotherform, the invention is further directed to encoding and decoding theundulating pressure waves with data communicated to and or from thewireless devices. The invention includes means for providing power andor data signals to embedded devices through application of undulatingpressure waves generated and or energized by opposing transducers, suchas ultrasonic transducers. In a representative implementation, such asin an aircraft or rocket fuel tank, the wireless device is embeddedinside fuel tank with wireless power and data communication from anexternal control unit. An embedded sensory unit could include anexemplar fuel level sensor. Both the internal embedded sensory unit andthe external control unit use respective transducers to communicatepower and or data through ultrasonic pressure waves transmitted througha coupling medium, such a the wall of the fuel tank. The embeddedsensory unit is preferably embedded in or attached to the internal sideof the exemplar fuel tank and the control unit is attached to theexternal side of the fuel tank so that no wires need be fed through thefuel tank wall thereby reducing the potential of ignition of the fuel bya faulty electrical wire. An internal embedded microprocessor would beconnected to both a sensing element and a power conversion element. Thetransducers are preferably piezoelectric transducers tuned to aparticular frequency. An internal transducer when energized byundulating pressure waves from an external transducer would provide anelectrical response signal to an electronic rectifier element to convertthe electrical response signal from the internal transducer to usefulelectric power to power the microprocessor, and any embedded connectedsensors or actuators. The ultrasonic pressure wave would be generated inthe structure by the external ultrasonic transducer tuned to thefrequency of the internal piezoelectric transducer of the embeddedsensory unit. The ultrasonic waves would excite an oscillation in theinternal transducer in the embedded sensory unit, and the oscillationwould, in turn, generate the electrical response signal which could bethen converted to a power signal of useful electric power to power theentire embedded sensory and or actuating unit. The energizing signal andthe resulting electrical response signal may also be appropriatelymodulated for the communication of digital data used for controlling theembedded microprocessors, sensors and actuators. In the preferred form,the power would then be used to activate and power the embedded sensorand or actuator and the digital signals could be used to control theembedded microprocessor to interrogate the embedded sensor or controlthe embedded actuator. The power signal would power any associatedembedded electronic components necessary for interpreting input datasignals from the external control unit and for generating output datasignals communicated to the external control unit.

Additionally, the embedded sensory unit could include microprocessingmeans for generating output data signals and include transducer drivemeans for activating the internal transducer for communicating data tothe external control unit connected to the external transducer. Theconverted power in the embedded unit could also be stored in an embeddedbattery or capacitor for longer term operations of the embedded sensoryunit. An internal battery would enable bidirectional data without theneed for transmitting power through the coupling medium. Data acquiredfrom the embedded sensor is also communicated by encoding the data inultrasonic waves generated by the same piezoelectric transducer used tocollect the input data and or power. The encoded waves would then becollected by an external transducer providing an external data signal tothe external control unit. The external control unit could communicatebidirectional data to the internal microprocessor for monitoring theembedded sensors and for controlling the internal actuators.

The primary advantage of the invention is the use of embedded activewireless sensors and actuators which can be integrated into structuressuch as composite motor cases, or propellant tanks without the use ofconnecting wires. The invention will also provide power and or datacommunication for devices embedded or enclosed in conducting materialswhere penetration of the radio frequency electromagnetic waves typicallyused for wireless communication is impossible or impracticable. Thesedevices can also be used in any other application where good undulatingpressure wave coupling is ensured. Additional applications includemonitoring of structures such as bridges or buildings, or of largevehicles such as ships or aircraft. These and other advantages willbecome more apparent from the following detailed description of thepreferred embodiment.

BRIEF DESCRIPTION OF THE DRAWING

The drawing depicts an ultrasonic power and data communication system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An exemplar embodiment of the invention is described with reference tothe drawing using reference designations as shown in the drawing. Anembedded sensory and actuating unit 10 is positioned in contact with anundulating coupling medium 11 which is preferably an ultrasonic couplingmedium 11 separating an external transducer 12a and an internaltransducer 12b opposing each other. The embedded unit 10 preferablycomprises an electrical isolation material such as cured rubber matrixmaterials for electrically isolating the electrical signals within theunit 10 from an environment in which the embedded unit 10 is disposed.

The internal transducer 12b generates an electrical response signal 13when energized by input ultrasonic waves 14a communicated from theexternal transducer 12a through the coupling medium 11 to the internaltransducer 12b. The internal transducer 12b also generates outputultrasonic waves 14b also communicated through the ultrasonic couplingmedium 11 to the external transducer 12a. The transducers 12 are membersof a group of transducers that transduce electrical signals to and orfrom undulating pressure waves 14. The coupling medium 11 could be anymedium that is capable of communicating undulating pressure waves 14such as audio, acoustical, subsonic, sonic and ultrasonic undulatingpressure waves tuned to an energizing frequency of the transducers 12.The transducers 12 generate the undulating pressure waves 14 over anysuitable frequency preferably from sub audio frequencies to radiofrequencies but of a particular frequency suitable for efficienttransmission of the energy of the undulating waves 14 through the medium11. The medium 11 could be any solid, such as metal, concrete, ceramic,epoxy, composite, any semi solid, such as rubber and gels, any fluid,such as water or fuels, or any gas, such as air and gas carriers, all ofwhich media 11 can communicate the undulating pressure waves 14. Theselected transducers 12 and medium 11 are application specific, butgenerally low frequency undulating pressure waves 14 travel farther thanhigh frequency waves 14. The distance between the transducers 12 is alsoapplication specific and based upon the type of transducers 12 selectedand the type of coupling medium 11 used in the application in view ofany application restriction on the placement location of the transducers12. Those skilled in the art of transducer device and system designs canreadily select suitable transducers 12, coupling medium 11 andtransducer separation distances to configure the coupling arrangementfor efficient energy transfer of power and or data signals between thetransducers 12 for a particular application.

The exemplar transducer coupling arrangement comprises piezoelectrictransducers 12a-b communicating power and data signals encoded in theultrasonic waves 14a-b through a solid medium 11 such as solid metalused in aircraft or rocket fuel tanks. The transducers 12a-b arepreferably opposing input output transducers 12 as both can be used tocommunicate bidirectional data, but multiple unidirectional transducers12 could also be used to provide full duplex communication using twopairs of unidirectional communicating transducers 12.

The transducers 12 and coupling medium 11 may be one of many types ofdesired coupling arrangements based upon specific applications. Forexample, the coupling arrangement comprising the transducers 12 andcoupling medium 11, may include piezoelectric transducers 12 preferablyfor generating ultrasonic waves 14 through a solid or a semi solid orliquid medium 11, ultrasound transducers generating sonic or ultrasonicwaves through semi solid human body tissue, tuned electro mechanicaltransducers 12 such as a spring suspended weights coupled to magneticinductors for generating low frequency waves 14 through a fluid,acoustic magnetic coil speaker transducers for generating acoustic waves14 through a semi solid, fluid or a gas medium 11, among many availabletypes of coupling arrangements. Hence, the coupling arrangement of thetransducers 12 and coupling medium 11 cover a wide scope of equivalentcoupling arrangements where power and or data is communicated through acoupling medium 11 communicating undulating pressure waves 14.

The opposing transducers 12a and 12b may produce collimated waves 14aand 14b, respectively, but alternatively and preferably have respectivelenses 15a and 15b for focusing the waves 14a and 14b onto respectiveopposing transducers 12b and 12a for concentrating power transfer andfor improving data reception through the opposing transducers 12b and12a. The lens 15a is shown by way of example as a typical refractivetype lens whereas lens 15b is shown as a curved transducer surface bothof which function to focus the waves 14a and 14b for efficient powertransfer to the opposing transducers 12b and 12a. The lens 15b andtransducers 12b may be an integral structure, for example, a curved 1.0mm thick piezoelectric transducer having a 15.0 cm focal length.

The electrical response signal 13 is communicated to a power conditioner16 for providing power to an internal processor 17 through an internalpower signal 18 which may also be communicated to a battery 19 or anelectrical energy storage means, such as a capacitor. The processor 17is preferably a power efficient microprocessor which preferably includeson board RAM and ROM for digital processing and further includes bothdigital and analog input output ports necessary for interfacing theprocessor 17 with the sensor 25 and the actuator 27. The battery 19 ispreferably a rechargeable battery, and could be a conventional nickelcadmium battery, but could also be a fixed life time battery used aseither a primary power supply for a fixed amount of time or as a backuppower supply used only during interrupted or discontinuous electricalresponse signals 13 providing power to the power conditioner 16.

In the preferred form, the power conditioner 16 provides power throughpower signal 18 to the internal processor 17 and to the battery 19during times when power is being received. The processor 17 may beintermittently active dissipating active power during active operationor dissipating little power when the processor 17 is inactive. Duringdormant periods, power may need not be received. When power is received,the power can be used to charge the battery 19 even when the processor17 is inactive in a dormant state. In alternative forms of supplyingpower, the power conditioner 16 could supply power to battery forcharging the battery 19 to store a sufficient amount of power to powerthe processor 17 only when active, in the case where the amount of powerdelivered through the power conditioner 16 is insufficient to directlypower the processor 17 when active, but is sufficient to charge thebattery 19 to such a storage capacity level that regular intermittentpowered operation of the processor 17 is practicable to achieve theprimary functions of the embedded unit 10. The processor 17 preferablyincludes programs for processing data and for sensor monitoring and oractuator control within the embedded unit 10.

The electrical response signal 13 may also include encoded data signalsand is preferably connected to an internal data input driver 20 forcommunicating data in signals 21 to the internal processor 17. Inalternative forms, the embedded unit 10 may include a separate pair ofpower transducers, not shown, such as transducers 12a-b for deliveringpower through ultrasonic waves 14a to the embedded unit 10 and anotherseparate pair of input data transducers, not shown, such as transducers12a-b for communicating only input data signals, through ultrasonicwaves 14a. The internal processor 17 is also preferably connected to aninternal data output driver 22 providing data out signals 23communicated to and energizing the internal transducer 12b providingultrasonic waves 14b having encoded output data communicated throughtransducers 12b to the external transducer 12a. In alternative forms,the embedded unit 10 may further include yet another separate pair ofoutput data transducers, not shown, such as transducers 12a-b forcommunicating output data through respective ultrasonic waves 14b.Depending on the type of drivers 20 and 22, power could also be routed,not shown for convenience, and delivered to the drivers 20 and 22through the power line 18 for powering the drivers 20 and 22 from eitherthe power conditioner 16 or the battery 19.

Preferably, the processor 17 communicates control and monitoring sensorsignals 24 to and or from an exposed embedded sensor 25, andcommunicates control and monitoring actuator signals 26 to and or froman exposed embedded actuator 27. The sensor 25 could be of a varietydesired types, such as a thermistor for sensing temperature of anenvironment, not shown, a resistive bridge strain gauge for sensingstress in a structure, not shown, fluid level sensors, pressure sensors,chemical sensors, humidity sensors, photo sensors and accelerometersensors, among many other types. The actuator 27 could also be of avariety of desired types, such as micro electrical mechanical fluidvalves and pumps dispensing and injecting fluids, human heartpacemakers, heaters for temperature control, optical transducers,ultrasonic transducers, piezoelectric transducers, vibration controltransducers, platform directional control transducers, among many othertypes. Those skilled in the art of sensor and actuator devices anddesigns know how to readily select and interface differing sensors 25and actuators 27 to processors 17 and power supplies 19 for operationsensing and actuation.

The sensor 25 and or actuator 27 receive power from the powerconditioner 16 and or battery 19. Some sensors 24 may not require activecontrol signals 24 but only provide unidirectional sensing monitoringsignals 24 to the processor 17 depending on the type of sensor used.Likewise, some actuators 27 may not provide actuating monitoring signalsbut only receive unidirectional actuator control signals 26 from theprocessor 17 depending on the type of actuator 27 used. In a preferredcommon mode of operation, the processor 17 under program control and inresponse to controller data commands encoded in data in signals 21 wouldprovide the actuator 27 with activation control signals 26 to activatethe actuator 27 causing an environmental change to be sensed by thesensor 25 which then provides sensing monitoring signals 24 to theprocessor 17 which then could in turn communicate responsive output datasignals 17a through the data out driver 22 for communicating status ofthe actuation of the actuator 27.

Further still, multiple embedded units 10, transducers 12, sensors 25and actuators 27 in various desired configurations are possible toachieve a desired bandwidth and multiplex operation. Such configurationsmay include a plurality of embedded units 10 with respective internalprocessors 17. Each unit 10 would receive communicated power and wouldcommunicate input and output data signals 21 and 23. Each of theembedded units 10 could have respective sensors 25 and actuators 27.While the present preferred form is described with reference to a singlepair of transducers 12a-b and a single embedded unit 10, the presentinvention can be easily extended to system networks and configurationsusing a plurality of respective transducer pairs 12a-b, processors 17,sensors 25 and actuators 27 in respective embedded units 10 distributed,for example, over a wide area using respective separate coupling medium11, or along a single elongated coupling medium 11.

The processor 17 may be connected to an embedded internal oscillator 29providing an oscillating signal 28 to provide the processor 17 withtiming signals for clocking and timing operations of the processor 17.The oscillator signal 29 could also be used by the processor 17 todemodulate input data on the data in signal 21 and or to modulate outputdata into the data out signal 23 for encoding of the output data intothe data out signal 23 for efficient transmission of the data out signal23 through the transducers 12a-b and coupling medium 11. There are manywell known modulation techniques available, such has conventionalsinusoidal modulation and digital modulation.

The embedded unit 10 is coupled through the transducers 12 and couplingmedium 11 to an external controller 30 which may, for example, comprisean external processor 31 also preferably including typical on board orconnected RAM and ROM, not shown, for digital processing and operationalcontrol over the embedded unit 10. The external processor 31 may be apersonal computer, central processing unit, or microprocessor, or likeprocessing means. The external controller 30 may be permanently mountedto the coupling medium 11 or could be a hand held unit which is manuallypositioned onto the medium 11 and then activated to command and orinterrogate the embedded unit 10. Typically, the external processor 31and the internal processor 17 function in a master-slave cooperation. Ina distributive system, not shown, the external processor 31 could be acentral processing unit commanding and controlling a plurality ofinternal microprocessors 17 functioning as distributed processorsoperating within respective embedded units 10.

The external processor 31 receives input signals 32a, transmits outputsignals 32b and transmits power control signals 33. The power controlsignals 33 are communicated to an external generator 34. The inputsignals 32a and output signals 32b are respectively connected to aseparator 35a and a combiner 35b respectively connected to drivers 36aand 36b. One or both of the separator 35a and combiner 35b may beconnected to a power modulation demodulation signal 37 generated by thegenerator 34. The separator 35a receives data out signals 38 from theexternal transducer 12a and the combiner 35b transmits data in signals39 to the external transducer 12a through the respective drivers 36a and36b. The driver 36a provides for necessary detection and amplificationto interface the data out signals 38 from the transducer 12a to theseparator 35a and or external processor 31. The driver 36b providesnecessary detection and amplification for energizing the externaltransducer 12a. The data out signals 38 from the external transducer 12abecome the data in signals 32a to the external processor 31 and the datain signals 39 to the external transducer 12a derive from the data outsignals 32b from the external processor 31. An oscillator 40 such as acrystal oscillator provides an oscillating signal 41 for clocking theexternal processor 31. A power supply 42 supplies power 43 to theexternal processor 31 and to the generator 34. The power supply 42 couldalso provide power to the combiners 35 and drivers 36 depending on thetype of combiners 35 and drivers 36 used.

In a power transfer mode of operation, the external processor 31provides generator control signals 33 to the generator 34 forcontrolling the amplitude, phase and or frequency of the power signal 37for efficiently transferring power from the supply 43, through thegenerator 34, through the transducers 12a-b to the internal powerconditioner 16 of the embedded unit 10. In the case where power transferis continuous, the external processor 31 need not actually control thegenerator 37 providing a continuous power signal through the driver 36bto the transducer 12a. In the preferred form, the power signal 37 andthe output signals 32 are communicated either simultaneously or throughtime division multiplexing over the data in signal 39 using a commoncombiner 35b, but a separate line and driver, both not shown forconvenience, could be used to separately communicate power and data overrespective separate lines to the energize one external transducer 12a ortwo respective external transducers 12a. The various methods ofsupplying of power to the internal processor 17 can also be applied tothe sensor 25 and actuator 27. Continuous or intermittent power can besupplied at differing times to the sensor 25 and actuator 27 from eitherthe power conditioner 16 or battery 19 during active operation of thesensor 25 and actuator 27.

In a data input mode of operation, the external processor 31 providesoutput signals 32b which may be modulated by a modulation signal 37using combiner 35b to energize the external transducer 12a through thedriver 36b. In a data output mode of operation, the external processor31 would receive the output signals 32a which may be demodulated by ademodulation signal 37 using separator 35a receiving through the driver36a the data out signals 39 from the external transducer 12a.

Proof of concept may be had using two opposing 0.5 inch diameter diskshaped piezoelectric transducers 12a-b submerged in water functioning asthe ultrasonic coupling medium 11. The transducers 12a-b are separated,for example, by 9.25 inches, and aligned so that ultrasonic waves fromthe transmitting transducer 12a are directed towards the receivingtransducers 12b. The transmitting transducer 12a is energized by a radiofrequency (RF) signal 37 from an RF generator 34 providing a 90.0 voltRMS sine wave signal at a frequency of 1.0 MHz. The receiving transducer12b is connected to a variable resistive load emulating the powerconditioner 16 which is connected to a 1.0 megohm input impedanceoscilloscope for detecting the electrical response signal 13 from thereceiving transducer 12b across the variable resistive load. As theresistive load 16 varies, for example, between 25.0 and 154.0 ohms, theamount of power transfer to the resistive load varies, for example,between 5.00 and 12.3 milli-watts. The electrical response signal 13from the receiving transducer 12b is a sinusoidal output which can berectified by conventional diode capacitor rectification circuits forconverting the sinusoidal electrical response signal 13 into asubstantially DC voltage and current power signal 18 that can be used tocharge a battery 19 and power the internal processor 17, sensor 25 andactuator 27. An excitation frequency from the generator 34 can be tunedto the specific type of transducer 12a to maximize the power transferfrom the generator 34 to the external transmitting transducer 12a to theinternal receiving transducer 12b and to the load 16. A rectificationcircuit 16 can be optimized to receive a maximum amount of power fromthe internal receiving transducer 12b to the battery 19 and internalprocessor 17. Moreover, the power conditioner 16 could be tuned to aspecific frequency such that the external processor 31 and generator 34could be used to selectively power a plurality of embedded units 10 byrespectively selective differing frequencies of the power signal 37.

Having verified that power transfer is practicable, it should now becomeapparent that such a sinusoidal excitation signal 37 from the generator37 could be used to modulate digital output signals 32b from theexternal processor 31 to encode input data into pulse modulated data insignals 39 using the combiner 35b which can be, for example, a frequencymixer or voltage summer. In such a case, the data in driver 20 couldfunction to square and digitize a resulting modulated pulse signal 13into digital square wave signals sampled by the internal processor 17for clocking input data into the processor 17. The driver 20 wouldfunction as an analog to digital converter. In another form, the data indriver 20 could be a peak threshold level detector or zero cross overcomparator providing a stream of digital data in signals 21 to theinternal processor 17. The frequency of the modulated pulses and theperiod of the pulses can be controlled by the external processor 31 toimplement a predetermine data format that the internal processor 17 usesto then decode the data in digital bit stream 21 into input data.Similarly, the internal processor 17 could provide a modulated pulsesignal 17a in the nature of digital square waves to the data out driver22 which conditions the square waves into sinusoidal data out signals 23for energizing the internal transducer 12b. The data out driver 22 couldfunction as a digital to analog converter. The data out driver 22 couldbe a one shot device providing data out pulses 23 of predeterminedduration. In another form, the data out driver 22 could be a voltagecontrolled oscillator providing a sinusoidal data out signal 23 from adigital signal 17a from the internal processor 17. In such cases, theexternal generator 34 may be used to demodulate sinusoidal data insignal 38 using the separator demodulator 35a then providing a digitalbit stream input signal 32a to the external processor 31. There are manywell known modulation and demodulation techniques available, includingfrequency modulation, amplitude modulation and pulse modulation wherebinary data bits are encoded into periodic and or modulated signals,among other types of modulation and encoding methods. Amplitudemodulation has advantages in that high power continuous waves 14 providefor high continuous power transfer yet can be amplitude modulated toencode data at the tuned frequency of the transducers 12 for maximumpower transfer and data bandwidth. Frequency modulation may also providemaximum power transfer because the frequency is modulated from a centertuned frequency of the transducer 12 while maintaining maximum amplitudefor power transfer. Frequency modulation is also a proven way tomaximize data bandwidth packing within short time durations. There maybe a trade off in design between optimum power transfer and maximum databandwidth. In the preferred form, the power signal 34 is a continuouswave continuously transferring power or alternatively a pulse waveperiodically transferring power to the embedded unit 10. The continuouswave is preferably amplitude modulated or frequency modulated to encodeinput data with power transfer. The pulse wave can be periodicallymodulated or pulse width modulated to provide encoded input data withpower transfer.

The present invention enables the communication of power and data froman external controller 30 to an embedded unit 10 through a couplingmedium 11 using opposing transducers 12a-b. Those skilled in the art canmake enhancements, improvements and modifications to the invention.However, those enhancements, improvements and modifications maynonetheless fall within the spirit and scope of the following claims.

What is claimed is:
 1. A system for communicating power, the systemcomprising,generator means for generating an energizing signal, firsttransducer means for transducing the energizing signal into undulatingpressure waves, medium means connected to the first transducer means,the medium means for communicating the undulating pressure waves, and anembedded unit means, the embedded unit means comprises:second transducermeans connected to the medium means, the second transducer means fortransducing the undulating pressure waves into electrical responsesignals; and power conditioner means for converting the electricalresponse signals into electrical power signals for delivering the power,the second transducer means and the power conditioner means areintegrated together in the embedded unit means for electricallyisolating the power conditioner means from the generator means, themedium means is also for separating and isolating the generator meansfrom the power conditioner means; sensor means powered by the powerconditioner means, the sensor means for sensing the condition of theenvironment; and processor means powered by the power conditioner means,the processor means for monitoring the sensor means for sensing thecondition of the environment.
 2. The system of claim 1 furthercomprising,a lens means disposed between the first transducer means andthe second transducer means for focusing the undulating pressure wavesonto the second transducer means for energy transfer of the undulatingpressure waves from the first transducer means to the second transducermeans.
 3. The system of claim 1 wherein the embedded unit furthercomprises a battery means for storing power from the power conditionermeans.
 4. A system for communicating power, the systemcomprising,controller means for generating an energizing signal as asource of the power, first transducer means for transducing theenergizing signal into undulating pressure waves, the energizing signalis tuned to a resonant frequency of the first transducer means, mediummeans connected to the first transducer means, the medium means forcommunicating the undulating pressure waves, the undulating pressurewaves are tuned to the resonant frequency of the first transducer means,second transducer means connected to the medium means, the secondtransducer means for transducing the undulating pressure waves intoelectrical response signals, the undulating pressure waves and theelectrical response signals are tuned to a resonant frequency of thesecond transducer means, and embedded unit for receiving the power fromthe controller means, the embedded unit comprises:a rectifier means forrectifying the electrical response signals into direct current powersignals for receiving the power in the embedded unit; sensor meanssensing by power received through the rectifier means, the sensing meansfor sensing the condition of the environment; and internal processormeans activated by power received through the rectifier means, theinternal processor means for monitoring the sensor and sensing thecondition of the environment.
 5. The system of claim 4 wherein theembedded unit further comprises a battery means for storing powerreceived through the rectifier means.
 6. The system of claim 4 whereinthe controller means comprises,a generator means for generating theenergizing signal, and external processor means for controlling thegenerator means to generate the energizing signal to provide power tothe embedded unit at differing times.
 7. A system for communicatingpower, the system comprising,a controller for generating an energizingsignal as a, source of the power, a first transducer for transducing theenergizing signal into undulating pressure waves, the energizing signalis tuned to a resonant frequency of the first transducer, a mediumconnected to the first transducer, the medium for communicating theundulating pressure waves, the undulating pressure waves are tuned tothe resonant frequency of the first transducer, second transducerconnected to the medium, the second transducer for transducing theundulating pressure waves into electrical response signals, theundulating pressure waves and the electrical response signals are tunedto a resonant frequency of the second transducer, and an embedded unitfor receiving the power from the controller means, the embedded unitcomprises,a rectifier for rectifying the electrical response signalsinto direct current power signals for receiving the power in theembedded unit, a sensor powered by the rectifier, the sensing forsensing the condition of the environment, an internal processor poweredby the rectifier, the internal processor for monitoring the sensor forsensing the condition of the environment, and a battery for storingpower received through the rectifier, the battery for delivering powerto the actuator when actuated, for delivering power to the sensor whensensing, for delivering power to the internal processor when activelymonitoring the sensor.